1. Field of the Invention
The present invention relates to a print head for a dot matrix printer of an armature attracting type, and more particularly to a supporting structure of the armature.
2. Discussion of Related Art
Japanese Patent Application Laid-open 63-78757 (hereinafter called first reference) and Japanese Utility Model Application Laid-open 63-106638 (hereinafter called second reference) disclose print heads each having a supporting structure of an armature to be pivotable.
The print head of the first reference comprises a sub-yoke provided on a rear portion of a main yoke and having a post formed thereon, and an armature having a hole engaged with the post.
In the print head of the second reference, a yoke has a recess for positioning an armature. The armature has a projection engaged with the recess.
In the first reference, it is necessary to engage the armature with the hole with a gap. Consequently, the armature is not accurately positioned because of the gap. Furthermore, a number of the manufacturing processes and the parts are required for forming the posts on the sub-yoke.
In the second reference, it is difficult to perform a finishing machining of a top face of a core mounted on the yoke and the bottom of the recess at the same level with accuracy. Since the contact area of the projection of the armature with the recess of the yoke is small while a gap between the projection and the inside periphery of the recess is large, the magnetic resistance there-between is large. Namely, the magnetic efficiency is low in the magnetic circuit.